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Exam 2
J. Ocular Fundus
59
Veterinary Medicine
Professional
10/21/2016

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Cards

Term
What are the parts of the fundus?
Definition
-retina
-choroid
-optic n
-sclera
Term
What is normal in regards to a fundic examination?
Definition
-tapetal fundus is always superior
-no tapetuc can be a normal variation
-amount of RPE and choroidal pigment vary with coat color
-all structures should appear CLEAR and CRSIP
Term
Why is the choroid pigmented? What is its normal color?
Definition
-inc melanocytes
-dark brown
Term
What does mild color dilution of the choroid look like? In which animals does it occur?
Definition
-orange/brown due to less pigment + choroidal vessels showing through
-animals with red coat color and chocolate labs
Term
What does a blue iris look like? In which animals does it occur?
Definition
-choroidal vessels against white sclera; red appearance and usually atapetal
-huskies
Term
Does a feline have an oddly large or small tapetal area?
Definition
-large
Term
Generally describe the retina.
Definition
-semi-transparent, thin, neurosensory tissue
Term
Can we normally see the retinal blood vessels?
Definition
-yes
Term
What would indicate elevation of the retina? What is the one exception to this rule?
Definition
-bulge in retinal vessels when visually followed
-exception = horse
Term
Where does the retina attach? Why is this clinically significant?
Definition
-only attached around the optic disc and peripherally where the retina meets the ciliary body
-large potential space for fluid and/or cell accumulation leading to retinal detachment & can tear and fall off the choroidal surface
Term
What is the optic disc?
Definition
-the visible portion of the optic nerve
Term
What does a typical feline optic disc look like?
Definition
-non-myelinated (small, dark, round)
-vessels do not cross the disc
Term
What does a typical canine optic disc look like?
Definition
-myelin varies (round to traingular & dark to white)
-vessels cross the disc
Term
What does a typical equine optic disc look like?
Definition
-large, horizontal oval
Term
What does a typical ruminant optic disc look like?
Definition
-dark, tannish color causing it to blend into background, to cream colored depending on species
-extremely large overlying vessels
Term
What is hyperreflectivity? What does it indicate?
Definition
-the tapetum appears hyperreflective when the overlying retina is thin
-indicates retinal atrophy due to inactivity
Term
What is hyporefflectivity? What does it indicate?
Definition
-the tapetum appears hyporeflecive when there is fluid and/or cells b/n the tapetum and retina
-indicates active disease
Term
What are the causes of a non-tapetal fundus in general? What do they look like?
Definition
-retinal atrophy/degeneration (inactive): apears depigmented
-active disease: appears blurry, out of focus with fluid beneath retina (hemorrhage or exudate)
Term
What does an electroretinogram measur? What is its purpose?
Definition
-measures respone of the photoreceptors to light
-tests for retinal degeneration
Term
What does an ocular ultrasound do? What does it specifically diagnose?
Definition
-images the position of the retina if it is not visible on fundic exam
-diagnostic for retinal detachment
Term
How does retinal disease usually affect the PLRs?
Definition
-usually a weak positive
Term
Between what two layers does retinal detachment occur?
Definition
-occurs b/n the RPE layer of the retina an dthe neurosensory retina
Term
What causes progressive retinal atrophy (PRA)? Is it bilateral, unilateral, or varies?
Definition
-genetic
-always bilaterally symmetrical
Term
At what age does PRA usually begin?
Definition
-5 years of age and blind by 8-9 years of age
Term
What is the physiology behind PRA?
Definition
-gradual degeneration of photoreceptors from rods to cones
Term
What is the first clinical sign of PRA?
Definition
-night blindness
Term
What clinical signs do we see on fundic exam of PRA?
Definition
-diffuse atrophy visible
-hyperreflectivity
-retinal vasculature attenuation
-pale optic disc
Term
What is SARDS?
Definition
-Sudden Acquired Retinal Degeneraiton Syndroe
Term
What animals are affected by SARDS?
Definition
-middle-aged to older dogs
Term
What is the clinical sign of SARDS?
Definition
-ACUTE onset of blindness (always bilateral)
Term
How does SARDS affect the PLRs?
Definition
-weak
Term
How does the fundus appear on examination with SARDS? How do we diagnose it?
Definition
-normal
-diagnosed bia electroretinogram
Term
How do we treat SARDS?
Definition
-we can't
Term
What is PRA?
Definition
-Progressive Retinal Atrophy
Term
Is PRA acquired or genetic? Bilateral or unilateral?
Definition
-genetic
-bilateral
Term
At what age does PRA commonly present? What is the age of onset? Why are these two values different?
Definition
-presents by 8-9 years
-onset at about age 5 y
-progresses over years
Term
How do the photoreceptors change over the course of PRA? HOw does this affect vision in the patient?
Definition
-rods to cones gradually
-night blindness first folled by day vision loss
Term
What kind of retinal degeneration commonly affects dogs with access to large animal dewormers?
Definition
-Ivermectin toxicity
Term
What are the clinical sings of Ivermectin toxicity evident on an optho exam?
Definition
-acute blindness with dec PLRs
-also see neuro signs if a greater overdose
-fundus appears normal
Term
How do we treat the visual deficits that occur with lowergrade Ivermectin toxicity? Explain the reasoning behind it.
Definition
-no treatment
-b/c vision returns normally within 48 hours (light vision then night vision)
Term
What is the doctor term for light vision?
Definition
-photopic vision
Term
What is the doctor term for dark vision?
Definition
-scotopic vision
Term
In which species do we usually see visual issues due to Enrofloxacin toxicity?
Definition
-cats
Term
What are the clinical signs see due to Enrofloxacin toxicity seen on an optho exam?
Definition
-acute, irreversible blindness due to retinal degeneration
Term
What is the physiologic cause of retinal degeneration due to retinal detachment?
Definition
-separated from the choroid (its nutrient source)
Term
What are the typical signs of retinal atrophy?
Definition
-hyperreflectivity
-retinal vasculatrue attenuation
-depigmentation in non-tapetal fundus
-pale optic disc if the retinal atrophy is extensive
Term
How do we treat retinal degeration in general?
Definition
-we can't, it can't be fixed
-sometimes give Ocu-GLO a non=proven nutriceutical but it doesn't hurt
Term
Definition: Rhegmatogenous
Definition
-retinal detachment due to a tear or hole in the retina
Term
Definition: Non-rhegmatogenous
Definition
-detachment due to chorioretinitis or hypertension
Term
What is the physiology behind rhegmatogenous retinal detachment?
Definition
-tear ro hole develops in the retina => vitreous leaks under the tear/hole => the retina detaches
Term
What are the possible etiologies behind rhegmatogenous retinal detachment?
Definition
-secondary to hypermature cataract
-complication following cataract surgery
-Breed: Shih Tzu and Boston Terriers
-Severe globe Trauma
Term
How do we treat rhegmatogenous retinal detahcment?
Definition
-laser retinopexy to "seal edges" and prevent further detachment
-retinal reattachment surgery
Term
What is the physiology behind non-rhegmatogenous retinal detachment?
Definition
-chorioretinitis inflammation => leaky choroidal +/- retinal vessels => fluid leakds under retina
Term
What are the three major etiologic categories responsible for non-rhegmatogenous retinal detachment? Give an example or two of each.
Definition
-Systemic dz: infectious or neoplastic
-Immunde-mediates: VKH or Equine Recurrent Uveitis
-Trauma
Term
What are the clinical signs of optic neuritis see on optho exam?
Definition
-optic disc appears hyperemic, blurry and protruding
-dilated pupil with no direct PLR or consensual PLR to other eye (afferent deficit)
-blind in affected eye(s)
Term
What are the three possible etiology categories responsible for optic neuritis?
Definition
-Immune-mediated: granulomatous meningoencephalitis
-Infectious: cryptococcosis, canine distemper
-Neoplasie: lymphoma
Term
What are the two most common types of optic nerve neoplasia?
Definition
-meningioma
-astrocytoma
Term
Describe the presentation of optic nerve disease.
Definition
-exophthalmia without globe deviation laterally
-optic disc may/may not appear abnormal
-blind
Term
How do we treat optic nerve neoplasia?
Definition
-exenteration
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